Microsoft co-founder Bill Gates urged the company's employees to make products that are accessible to people worldwide. Here, Mr. Gates prepares to testify before a Senate subcommittee hearing on diplomacy, development, and national security on March 26, 2015.

Microsoft co-founder Bill Gates marked the company’s 40th anniversary on Saturday with an e-mail to all Microsoft employees. The note, which was posted on Twitter, hearkened back to Microsoft’s early days, when Mr. Gates and Paul Allen set the goal of putting “a computer on every desk and in every home.”

At the time Microsoft was founded, computers were used mainly by hobbyists, universities, and the government, so their goal was an ambitious one – but over the next several decades, personal computers went from being a niche product to being a home and office necessity.

In his e-mail to Microsoft staff, Gates didn’t spend nearly as much time dwelling on the company’s past as he did speculating about its future. He emphasized the importance of accessibility in computing, writing that “I hope you will think about what you can do to make the power of technology accessible to everyone, to connect people to each other, and make personal computing available everywhere even as the very notion of what a PC delivers makes its way into all devices.”

Gates noted that computing has evolved quickly in the last 10 years, from networked personal computers to an interconnected web of computers, tablets, smart phones, and other devices such as home appliances and cars. He also noted that the pace of technological change will continue to accelerate. “We are nearing the point where computers and robots will be able to see, move, and interact naturally, unlocking many new applications and empowering people even more,” we wrote in his letter.

The former chief executive officer urged Microsoft to use its resources and expertise to ensure that advances benefit as many people as possible, not just those able to afford cutting-edge devices. The company’s emphasis on accessibility is evident in recent products such as Skype Translator, which provides automated audio and text translation and allows people speaking different languages to communicate with one another nearly in real time, and HoloLens, a head-mounted virtual reality device that users can control with their eyes, voice, and gestures.

The letter says that Gates hopes Microsoft products will allow more people and organizations around the world to use technology. “Technology is still out of reach for many people,” he wrote, “because it is complex or expensive, or they simply do not have access.”

Gates stepped down as chairman of Microsoft in 2014, becoming an advisor to CEO Satya Nadella. Now worth approximately $80 billion, Gates works full time for the Bill and Melinda Gates Foundation, a philanthropic organization dedicated to enhancing healthcare and reducing poverty around the world.